This invention relates to disk drive systems. More particularly, the invention relates to the protection of disk drive actuators from mechanical shock forces.
Disk based data storage devices for storing digital electronic information have been in use in the computer industry for several decades. The storage devices operate by storing digital information on magnetic disk media, which can be either rigid or flexible and are mounted on a rotating hub. These storage devices are commonly referred to as disk drives. Disk drives come in two varieties: removable media and fixed media drives.
Removable media drives accept the disk media in the form of a removable cartridge. When the cartridge is inserted into a disk drive, a spindle motor in the drive couples with the disk hub in order to rotate the disk within the cartridge at a given speed. The outer shell of the cartridge typically has a media access opening proximate one edge. The access opening provides the recording heads of the drive with access to the disk. To cover the head access opening when the cartridge is not in use, a shutter or door mechanism is provided that prevents dust or other contaminants from entering the cartridge and settling on the recording surface of the disk. The shutter is commonly biased to a closed position with a spring bias. To open the shutter and gain access to the media, the drive employs a mechanism that overcomes the spring bias. In fixed media drives, by contrast, the disk hub is permanently attached to the spindle motor.
Disk drives typically employ either a linear actuator mechanism or a rotary actuator mechanism. The actuator positions the read/write head(s) of the disk drive on the recording surface(s) of the disk. The linear or rotary actuators must be able to move off, and away from, the storage medium to a retracted position, also commonly referred to as the parked position. This retracted position prevents damage to the head(s), for example, when a cartridge is inserted and removed from the disk drive or when the drive is moved. Moreover, many removable cartridge disk drives employ a pair of opposing read/write heads for recording and reproducing information on both sides of a storage medium. Typically, the opposing heads are disposed on flexible suspension arms at the distal end of an actuator that allow the heads to fly closely over the respective surfaces of the rotating disk.
Increasingly, disk drives must meet rigorous mechanical shock and vibration standards. Rigorous standards are necessary because current drive applications include hand held computers, digital cameras, and other portable computer appliances. The portable nature of these applications increase the likelihood that the drive will be subject to shocks and vibrations. For example, the computer appliance may be dropped or jarred. When experiencing mechanical shock or vibration, the actuator could inadvertently move from its retracted position causing serious damage to delicate drive components.
The protection of actuators from mechanical shocks and vibration has been addressed by prior art mechanisms. For example, U.S. Pat. No. 5,404,257 (Alt) has used an inertial latch mechanism that allegedly prevents a disk drive actuator from moving out of a retracted position during mechanical shocks. The Alt inertial latch mechanism accomplishes this feat by employing an inertial body and pivotable latch member. When a mechanical shock is experienced by the drive, the shock force causes the inertial body to contact the latch. As a result, the latch member closes on an abutment on the actuator and prevents it from moving completely out of the parked position. The latching is accomplished with out the aid of electrical power.
There are drawbacks to the prior art inertial latch mechanisms. For example, in the case of a series of shocks, the actuator may travel slightly away from the desired park position with each shock. Because there is no mechanism to return the actuator to the fully parked position, eventually, after the series of shocks, the actuator may travel out of the reach of the inertial latch. The result is that the inertial latch could fail to close on the actuator abutment during one of the shocks, resulting in failure of the inertial latch mechanism and damage to the drive.
Thus there is a need for an improved inertial latch mechanism that overcomes the drawbacks of the prior art.